Platinum nanoparticle growth with ALD and passivation-gas-incorporated ALD. Source: Volkswagen

The high cost of fuel cells, which poses a barrier to their wider diffusion in the automotive sector, is attributed to the use of platinum as a catalyst. As the catalytic process only occurs on the surface of platinum particles distributed on carbon powder, a large percentage of this cost-intensive metal is wasted.

Volkswagen and Stanford University researchers have developed a less-expensive, high-efficiency fuel cell technology to overcome this cost constraint. The team used carbon monoxide as a passivation gas during atomic layer deposition (ALD) of platinum atoms on a carbon surface, yielding extremely thin particles. The passivation process promotes 2D growth, leading to platinum nanoparticles with suppressed thicknesses and a more than 40% improvement in platinum surface-to-volume ratio.

The scheme reduces the amount of platinum to a fraction of the amount currently required and increases the fuel cell catalyst efficiency by a factor of three compared to available technology. This approach to synthesizing nanoparticle platinum/carbon catalysts achieved high platinum mass activities for the oxygen reduction reaction, along with excellent stability likely facilitated by strong catalyst–support interactions afforded by the synthesis technique.

ALD is also useful for a range of other applications requiring high-performance materials, such as next-generation lithium-ion batteries as well as conventional batteries.